- K. K. Verma, Ph. D. and Rashmi Saxena, Ph. D.
Retd. Professor of Zoology, HIG I/327, Housing Board Colony,
Borsi, Durg, M.P., 491001, INDIA
Eubios Journal of Asian and International Bioethics 7 (1997), 130.
One fundamental principle, which biologists have been having with them throughout this century, is that a cell in the body of an individual may be showing the structure and function of a muscle cell or a nerve cell or an epithelial cell, but it has the same hereditary mechanism, and, therefore the same genetic potential as any other cell in the body. The first cell, marking the beginning of existence of an individuals, is a fertilized ovum. It undergoes a long series or mitoses to give rise to the various cells in the adult body. In every mitosis the chromosomal material divides equally quantitatively as well as qualitatively. The visible changes in mitosis provide a strong basis for the belief that all cells have the same genetic potential. As an effect of its chemical environment (provided by hormones and organizers) some genes in a particular cell group become functional, while other genes remain dormant. The situation is well illustrated by the case of giant chromosomes in the salivary glands of some dipterous larvae. When a larva is in an intermoult period, in a giant chromosome some loci show puffing, which is a morphological expression of gene activity. When moulting starts, some old puffs are withdrawn, and some new ones are formed, indicating that some genes are going inactive and some others are activated. This change in genetic activity of puffing pattern can be produced also by injecting insect moulting hormone into an intermoult larva.
The principle that body cell, though having restricted and specialized function, has all the genetic potential of the species, has been mostly of the nature of a theory, fringing on a hypothesis. The successful cloning experiment by the Scottish workers has firmly and directly demonstrated the correctness of the theory by showing that the nucleus of a somatic cell (an mammary gland cell in this case) could guide the origin of all the different types of cells, present in the body of an adult sheep. Is it not a great scientific event?
Another biological principle, which has found support in the cloning of sheep, is that the genetic mechanism is relatively insulated from changes in the body. The French biologist, Lamarck, who came before Darwin and who also spoke of evolution, had a different opinion in this context. According to him changes, acquired by a individual through environmental effects, become absorbed in the genetic make up to some extent. This view of Lamarck has come to be known as Lamarckism, and has been the subject of a long and bitter controversy. It has not met with general acceptance among biologists. Critics of Lamarck in the last century were even led to make such gross statements as that, if Lamarckism were correct, a son of a blind man should be blind and a son of a lame man should have the corresponding limb deficiency since birth. At the cellular level the body of a cell is the cytosome, and cytosomal differentiation into that of a muscle cell or a nerve cell or of an epithelial cell, should correspondingly affect the genetic mechanism in the cell nucleus, if Lamarck were correct. The Scottish experiment can lead to experiments to show that the genetic potentials in the nucleus remain unaffected inspite of somatic cell differentiation.
The human spirit of quest and enquiry should
not be curbed, and at the same time it is necessary to seriously
discuss ethical and social consequences before a scientific finding
is applied to solving human problems. It is heartening to learn
that the US Bioethics Commission recommended in June 1997 that
cloning of a human being is ethically unacceptable, but experiments,
aiming at human cloning, should be allowed to continue up to the
in vitro embryo formation stage.